Palm Desert, California (CNN) -- It was mild curiosity that drew John Virgin and his son Bryce to the flashing lights and commotion of an accident scene near their home.

In the back of John's mind was his older son, Grant, who had gone for a walk nearby minutes earlier.

He gestured to an emergency medical technician to ask what happened.

"I called him over and I said, 'My son was walking over this way,' and he said, 'Describe him,'" said John. "I said, 'Well, he's 6 feet tall and has hair color just like mine,' and then he pointed at Bryce and said, '...and looks just like him.'"

John looked down at the area that had been cordoned-off -- the pavement covered with blood -- and his heart sank.